Radio receiving apparatus



March 3, 1931. L. Q. sLocu B 1,794,739

RADIO RECEIVING APPARATUS Origihal Filed Marh 27, 1925 2 Sheets-Sheet 1 March 3, 1931. L. Q. SLOCUMB RADIO RECEIVING APPARATUS Original Filed March 27, 1925 2 Sheets-Sheet 2 Patented Mar. 3, 1931 1 794 739 LLoYn Q. snooumntor rnneuson, MISSOURI V nanroinncnrvme ArrAnA'r s Application-filed. March 27 "19 25, Seria1 no. 18,661. Renewed July 18, 19 30.

I This invention relates to radio receiving Another lead-80f said coil 4 connects 1 apparatus, and with regard toce-rtain more to one end" ofthe primary P1 of an audio specific features to a receiving circuit and and radio frequency amplifying transformmeans for adjusting the same; a er 9. The primaryPl is shuntedby a fixed 5 ,Among thesev eralobjects of the invention condenser of approximately .002t-M.

may benotedthe provision of an improved capacity, serving the .usual purposes, such reflex circuit adapted to amplify modulated as to 1 secure undistorted reception with inradio frequency waves throu h a set of radio creased volume. c and audio frequency transformers, rectify My means of lead 11 primary P1 of transa S 10 these waves and amplify the resulting audio former 9 is connected-to a primary coil P2 60 frequency wave through the same set of radio of a second audio. and radio frequency'amand audio frequency transformers, theproplifying transformer 12 which primary coil vision of reaction and other stabilizing means P2 has shunted thereacross a constant ..001 4 for making'operable the elements of said cir- M. F. condenser 10*. The condenser ,10" I I cuit,and' means for readily controlling the serves purposes similar to those of 'con operation'of said elements: denser 10., p v I The invention accordingly comprisesthe The lead llalsoalfords connection with features of construction, combinations ofelethe sound reproducing instrument 13 The ments, and arrangements of pa-rts'which are instrument 13 is shunted by a .0005 exemplified in the circuit andstructure hereinafter described andthe application of which passage of radio frequency but not'audio will be indicated in the following claims. frequency. v r 1 Inthe accompanying drawings, in which The primary coil P2 andthe instrument is shown oneof variouspossible embodiments 13 complete their circuits with the plates 91 of theinvention, V and 93' of audion tubes 16 and 18 respec- 5 Fig. 1 is a circuit diagram; tively. r 1 F g- 2 is an a g P w h l g The said secondary circuit, of which coil combination control for a condenser and 2 is an element, has in series with said coil plate coils;v ,i V 2a grid 14' of the said audion tube 7. y In Fig. 3isan elevation of Fig. 2; series with said coil 2 is alsoa 0-50 megohm 8 g 418 a sectionalfdetailof ar o at variableresistance 19, said resistance being and y I I parallel with 'both'a .0001 M. F.. fixed con-- Fig. 5 is a plan view of the rheostat shown denser 20 and the secondary winding S3'of in Fig. 4:: p a third audio and radio frequency trans- 1' now more. p l y gv former 21.7 The transformer 21 serves re 1 there is shown a tapped e011 1 of approxifl i purposes to b ib A i hmately turns connectedm' genes Wlth the cated in the drawin s, the transformers 9.. usual. aerial ground circuit This coillselivgs 12 and 21.are prefe f'ably of the iron core as the primary; of alloosely coupled circuit yp q p m anapproxlmately 6817111211 In series With said resistancef1 9is a lead My 0011 QSh-UntQd by a"00025 vana-bleaco'nl 22 This lead 22- has two branch leads '23 denser 3. Th1scondenser3 serves tunmgpure. 24. Th 1 d 23 t on de of the poses. The primaryc0il1and the secondary n ii g. 51 f coil 2 are wound upon the same form. secon my C01 0 e m 1 5 Inductively connected with thesec-on'dary coil 2 is a 100 turn reversed feedback or reaction coil ladapted to regeneratively stabilize or resonate the loosely coupled circuit.

The reaction coil 4 is connected b a lead 5 to the plate Gof'an audion tube side of theseco'ndary coil S2 of the second amplifying transformer 12.

The secondary S1 is in series With a grid 15 of the audion tube 16 and has shunted thereacrossa constant one megohm 'resist- 100 condenser 10". ,The condenser 10 permits transformer 9, and the lead'2 l goes to one 5 nection to the minus side of the 6 volt (low voltage) filament lighting battery'26.' The battery 26 lights the filament 101. of arectifying tube 27 of a reflex circuitconnected to said loosely coupled circuit, as wellas the filaments 103, 105 and 107 of tubes 7, 1 6 and 18 respectively. A variable resistance 39 controls the filament 101 of the tube 27.

A'lead 28 from said lead 24 connects with the plus side of an 8 volt battery 29' (high voltage). The battery 29 is in the platecircuit of the detector or rectifying tube 27.

. The lead 28 has in series therewith a one M. F. fixed condenser 32 which has been found to quiet the battery noises.

' The minus side of battery 29 connects with the plus side of battery 26 and also to the minus side of a high voltage battery 30by way of lead 44. .Battery 30 has about 110 volts pressure and is used on the said loosely coupled amplifying circuit. Shunted across battery 30 is a fixed one M. F. condenser-109. The positive sideof the battery 30, by means of a lead 36, connects with a one turn primary winding 33 which controls the circuit of the detector tube 27. A return lead 35 from said coil 33 is connected to the aforesaid lead 11. The lead 11, as has been described connects with the plates of tubes 7, 16 and 18 in the first named loose coupled circuit. f r

The minus side of battery 30 is connected by means of lead 44 with the positive side ofbattery 26. The lead 44 serves as a common return for the current which goes to the fila ment of the tubes 7, 16 and 18fro1n the minus side of thebattery 26.

Cooperating with the single turn primary coil 33 is a 68 turn secondary coil 34. One end of the coil 34 leads to a combination grid leak and fixed condenser 37. The combination 37 has its component values fixed by the particular tube being used in the detector circuit. The combination 37 is in series with a grid 38 of the detector tube 27.

The other side of the secondary winding 34 leads to the plus side of the battery 26, already mentioned in connection with the fila ment lighting circuits;

The secondary coil or winding 34 is shunted by a variable condenser '51 ofapproximately .00025 M. F. capacity serving tuning purposes.

A reaction coil 50 cooperating with the secondary coil 34 leads, on one side, to the plate 40 of detector tube 27 and on the other side leads totheplus side of battery 29 by way of the primary P3 of the said third audio and radio frequency transformer 21. The primary P3 is shunted by'a fixed condenser 41 of approximately .004 MPF. capacity for permittingppassage of .radio frequency.

Before considering the operation of this en- 'tire circuit it should be noted that the transformers 9, 12, and 21 are of the continuous core type, and both radio and audio frequencies may be transformed therein. 3

V The-action is as follows:

V Modulated radio frequencies or signals are received in coil 1:by means of the usual aerial circuit. These signals are transmitted to, or induced in coil 2 which feeds into tube 7. The outputofthe plate 6 or tube 7 feeds throng-lithereactioncoil 4, some of the energy being used preferably to stabilize the m plifying circuit. However it'may be desirable to amplifyit sometimes. a

The balance of theenergy passes out through the transformer 19 into the tube 16: By means of the transformer 9 amplified radio and audio frequencies are transmitted to the tube 1 6. r 7 i The output oftube l6'passes through the transformer 12 which again transmits aniplified audio and'ra-dio frequenciesto the tube 18.- i

The amplified modulated radio'frequency output of tube 18 by-passes' the phones through the condenser 10?) and feeds into the single turn loop 33. I

It should be noted that the platesoftubes 7 16 and 18 are arranged in cascade and feed into lines 11 and 35 so that if th ereis a tendency for one tube. to oscillate it will be steadied by the others.

The primary coil 33 feeds into thetuned circuit of secondary'coil 34. The coil 34 is provided with, the reaction coil 50 forthe pur pose of boosting or stabilizing oscillations. It is also shunted with the usual variablecondenser 51 of about .00025 M. F. capacity.

The tube 27 rectifies the input wave and an audio frequency is fed through the transformer 21, through the resistance 19 and back into tube 7. V

From tube 7 the audio frequency wave traverses the tubes 7, 16 and 18 as well as the transformers 9 and'12.- Since the said trans formers operate on electromagnetic principles as well aselectrostatic, this wave readily passes through them. i

The aforesaid process of amplification is again gone through by the audio frequency primary P3 of transformer 21 was shunted.

through the condenser 41. It is believed however, that some leaks over to the loose coupled circuit of coil 2 and assists the original impressed radio frequency wave, thereby compensating for the usual inefficient action of continuous core transformers on radio frequency waves. Of course there is little difficulty experienced with these transformers. v

transm tsan amount jo'fcurrent to the discs on audio frequencies.

Thus it is evident that this complete circuit provides means for amplifying both radio and audio frequencies with the same set of transformers. A number of parts are eliminated with equal or better volumes and distance attained by the set. I

I The resistance 19 is an effective throttling device for stabilizing the loose coupled circuit of coil 2.

Attention is called tothefact that all lamp filaments are cascaded from the battery 26 but separate resistance control rheostats are provided for the rectifying tube 27 and the amplifying tubes of the loos-e coupled circuit of coil 2.

In order to provide easy control of this circuit certain novel features have been introduced.

In tuning the circuits of coils 2 and. 34 the two condensers 3 and 51 must be adjusted.

Also, the coils 4 and 50, which'are of'the plate type must-be adjusted. In order to facilitate making these four adjustments with two hands at one operation I providethe' combination depicted in Figs. 2 and 3. By way of examplethe elements of the first loose coupled circuit of coil 2 are used.

The variable condenser 3 isfixed to a slidable plate 60. Said plate mounted slidably in guides 61 and 62. These guides are fastened to a suitable element of the circuit equipment. The adjusting shaft 66 upon which is mounted the adjusting dial 67 eX- tends through a slot 68 in said element 70.

Mounted on the condenser by means of one of the spacer bolts 64 and spaced away from saidcondenser by means of a spacer collar 65 is the reacting coil 4 which is of the plate type. Below this coil 4, but not in movable connection therewith is the combination plate of coils 1 and 2. V 7

Obviously, adjustments may be made on the condenser 3 with the hand by means of the dial 67 and simultaneously with the same hand the coil 4 may be slidably arranged in various positions with respect to the coils 1 and 2. I

A like arrangement is provided for the condenser 51 and coils 50, 34 and 33 and so the four adjustments may be made at once.

An extension 71 fastened to the condenser dials permits of fine adjustment of the condensers Without causing coil adjustments. The rheostat 19, since it is a critical ele ment of the circuit, is ofthe graphitic type shown in Figs. 4 and 5 where-"an insulating disc 75 is shown mounted'upon a shaft 76. It is mounted between two conducting discs 76 and77. Between thesediscs and-in con tact therewith is a circular wedge of graphite 78 mounted upon said insulating disc; A wiper 79 forms one-terminal of the apparatus and transmits current to the 1 graphite 7 8 when in contact therewith and the graphitev and consequentlyto the shaft 80 uponwhich they are mounted proportional to thethickness of graphite at a given point of i contact of the wiper. A fine control is thusestablished'. The shaft 80 to which discs 76 and 77am fastened formsthe other terminal vso of the" apparatus. A notch at-the endof the graphite wedge audibly indicates when contact has been brokenbetw'een the wiper 7 9 and, the wedge-'TS-whichis to say, when all the resistance is in. This device-servesas an effective, closely controllabledampingap-.

edge of graphite 78 over the uncoated surface o f -the disc 75; It is intendedfthat there should be a; portion of the disc? 5 always clean of any carbon so that an'extremely high reparatus. The notch 81 also serves to keep I the wiper 79 ,from spreading'thefine feather ,si'stance may be obtained byallowing the ing out the above constructions without dey intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim: V 1. In a receiving circuit including a sound aerial ground circuit a loose coupledcircuit cooperating inductively with the aerial circuit by way of a secondary coil and a reaction coil-for the secondary coil; said loose parting from the scope of the invention, it is reproducing device, the combination of an 1 coupled circuit including a stabilizing resistance, a plurality of audion tubes and audioand radio-amphfying transformers,

a tuned circuit, a tuning primary winding 7 for said tuned circuit, means for connecting said reaction coil in parallel through the primaries of said transformers and through said sound reproducing device to the plates of at least some of said tubes, the grids of said tubes being in parallel circuit with said secondary coil byway of the secondaries of said transformers; a battery connecting with j the primary winding for the tuned circuit and supplying the filaments of said tubes in parallel; a tuned secondary coil for said tuning primary windin a reaction coil therefor; said tuned circuit including a rectifying 4 V Liven-739 tube', a:n'd means-for supplyingsaid loose coupled circuit with energy from said tuned cira cuit Way of said stabil-i-zingresistance;

2; n areceiving circuit including a sound reproducing device, the combination of anaerial ground circuit; a loose coupled circuit cooperating inductively with the aerial circuit-byway of a secondary coil anda reaction coil for the secondary-coil; said loose coupledcircuit including a pluralityof audion tubes and audioand radio-amplifying transfm'mers,- plates, filaments and grids for said tubes, atuned'circuit, a tuning primary Winding for said tuned circuit, meansfor 7 connecting said reaction coil through the primaries of'said transformers and throughsaid reproducing device to the plates of at leastsome 0i saidtubes, the grids of said tubes being in circuit With said secondary coil by-Wa-y oiiithe-se'condaries of said trans- ,formers; a battery-connecting With the primary Winding forthe-tuned clrcuit and supplying the filamentsof said tubes; a tuned secondary coil: for said tuning primary Winding; a reaction coil therefor; said tuned cir-v cuit including a rectifying tube, and means for supplying said loose coupled circuit with energy from said tuned circuit.

In testimony whereof, I have signed my name to this specification this 24th day of March, 1925; V y

LLOYD Q JSLOCUM-B. 

